Endocrine Abstracts

Objective: Insulin-like growth factor 1 (IGF1) is associated with metabolic parameters and involved in glucose metabolism. Low IGF1 has been implicated in the etiology of glucose intolerance. However, epidemiological data are scarce and the role of IGF1 in prospective studies is not clear to date.

Research design and methods: We measured IGF1 levels in 7665 subjects free of diabetes from two German prospective cohort studies, the DETECT study and SHIP and assessed incident diabetes mellitus during follow-up.

Results: There were 464 cases of incident diabetes during 32 229 person-years. There was no heterogeneity among both studies (P>0.4). The hazard ratio (HR) of incident diabetes in subjects with IGF1 levels below the 10th or above the 90th age- and sex-specific percentile, compared to subjects with intermediate IGF1 levels were 1.45 (95% CI 1.11–1.89) and 1.39 (1.05–1.84), respectively, after adjustment for age, sex, smoking status, education, family status, physical activity, alcohol consumption, and study. After further adjustment for hypertension, glucose, dyslipidemia, and waist-to-height ratio, the HR for low IGF1 became insignificant. Analysis of quintiles of IGF1 percentiles revealed a U-shaped association with incident diabetes. If high and low IGF1 was included into a prediction model of diabetes, high IGF1 remained a significant predictor.

Conclusions: Subjects with low or high IGF1 levels are at increased risk of developing diabetes. High IGF1 is an independent predictor of diabetes.